<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>4-超时与取消请求</title>
  </head>
  <body>
    <button>发送请求</button>
    <button>取消请求</button>
    <script>
      let btns = document.querySelectorAll('button');
      let xhr;
      btns[0].onclick = function() {
        xhr = new XMLHttpRequest();
        xhr.open('get', 'http://127.0.0.1:8081/delay-server');
        xhr.send();
        xhr.timeout = 4000;
        xhr.ontimeout = () => {
          console.log('请求超时');
        }
        xhr.onreadystatechange = () => {
          if (xhr.readyState === 4) {
            let text = xhr.responseText;
            console.log(text);
          }
        }
      }
      btns[1].onclick = function() {
        xhr.abort();
      }
    </script>
  </body>
</html>
